Conductor Roll -- Copper Coating

[Stephen Booth]

Hi Everyone,

Questions on an application in an Electrolytic Galvanizing Line Plant (EGL).

Component Name: Conductor Roll (diameter 600 mm, face length 4000 mm)

Roll has a coating or cladding of copper on the outside diameter (at least 10 mm thick) for conducting electricity during the plating process.

The top layer (over the Copper) is typically Chrome plating (web search shows this is often replaced with an HVOF coating)

My big question: Other than copper plating the roll, is there a Thermal Spray or Welding method and material that will satisfactorily replace the copper. I am directing this question to those of you out there who have experimented, and understand the function of the roll, and know the degree of purity of the copper cladding required. Thank you in advance for you help.

[Stuart Milton]

Hi Stephen,

We have a video from around the 1960's (maybe 1970's judging by the hair styles of the operators) of this exact application being done by our service division at the time.

We arc sprayed copper up to 30mm thick after a bond coat was applied. The rolls were linished, copper plated, ground, chrome plated and finally ground again. It may be that with todays arc spray and grinding technology, the middle copper plating process could be skipped.

If you're interested, I can have a go at extracting that section of the video and emailing it to you.

[MichiganMan]

To answer the original question, I would say that plating to 10mm thick is something that I haven't seen at any steel mill of any reasonable size, ever. It may have been common years ago to do this, but there is decent commercial access to thermal spray equipment now and builds this thick can be accomplished much more efficiently by spray than plating.

I would suggest doing the copper plating anyway if you are arc spray the roll though. It would seem to me that the copper plating is acting almost like a sealer for conductivity rather than porosity (if that remotely makes sense). The better the conductivity of the roll, the fewer production defects in the coil and the more money the EGL makes therefore the more they like you.

[Stephen Booth]

Thank you all for the answers.

So it seems that both MichiganMan and Stuart suggest

1. Bond Coat
2. Copper Build up to thickness with Arc Spray
3. Copper Plating (for lack of better term) as a sealant
4. Top coat by ??? HVOF CrCNiCR or Chrome Plating

BTW, several of the major players in the EGL OEMs seem to be using the term copper plated?!

Thank you both very much, Stuart, no necessary on the Video, I can visualize the concept, and it would be so much work to convert to digital